Propeller.



H. D. F. BAGLEY.

PROPBLLER.

APPLICATION FILED JULYZG, 1912.

Patented Dec. 2, 1913.

WITNESSES ATTORNEYS HERBERT D. F. BAGLEY, OF HOLLAND, MASSACHUSETTS.

PROPELLER.

Specification of Letters Patent.

Patented 10cc. 2, 1913.

Application filed July 26, 1912. Serial No. 711,657.

To all whom it may concern:

Be it known that I, HERBERT D. F. BAG- LnY, a citizen of the United States, and a resident of Holland, in the county of Hampden and State of Massachusetts, have invented a new and Improved Propeller, of which the following is a full, clear, and exact description.

The object of my invention is to provide a propeller having a maximum of efficiency in developing speed from a given power, and to provide a form and arrangement of blades that will present a maximum of surface to the water at the hub and yet minimize the cavitation.

The invention will be particularly explained in the specific description hereinafter to be given.

Reference is to be had to the accompanying drawings forming a part of this specification, in which similar characters of reference indicate corresponding parts in all the views.

Figure 1 is a perspective view of a propeller embodying my invention; Fig. 2 is a cross section through one of the blades, on the line 2-2 of Fig. 1; and Fig. 3 is a section through the blade at about right angles to Fig. 2, on the line 3-3 of Fig. 1.

In forming a propeller in accordance with my invention, I provide a series of blades 10, preferably three in number, and each blade is made cup-shape, being generally of concavo-convex form. The concave face 10 of the blade presents a curve of increasing radius from the base line outwardly to a point beyond the transverse center of the blade, and then presents a curve of decreasing radius to the outer edge. The said outer edge presents a convex curve at the front edge portion 11 beginning from the base, at 12, said convex front edge curve being of increasing radius toward the outer end of the blade, the convex edge of the said outer end presenting a curve of gradually decreasing radius from a point 13 forward of the longitudinal center to a point on the rear edge 14 within the transverse center; the said rear edge from the point 15 inward of the transverse center presents a concave curve 16, as shown best in Figs. 2 and 3, from the said point 15 to the base line. Transversely, the concave surface of the blade, as shown in Fig. 2, presents a curve of increasing radius from the forward edge 11 to the longitudinal center line, represented in Fig. 1 by the section line 3-3, and the curve being of decreasing radius from the center to the rear edge 14-. The rear edge of one blade extends at the base line to a point in line with the forward edge of the following blade, and the formation at the rear portions of the blades, including the decreasing transverse curve of the concave face, and the convened inner portion of the rear edge adjacent to the base line, results in the water being deflected from a blade within its transverse center to the next blade, and thus, although a maximum surface is presented to the water adjacent to the bases of the blades, the possibility of cavitation is minimized.

By giving the blade a radial curvature which increases in degree toward the tip, the water is thrown inwardly instead of outwardly, and by increasing the degree of the transverse curvature of the blade from the cutting edge to the trailing edge, the water as it leaves the blade is directed rearwardly instead of tangentially. By reason of the foregoing explained effects, the water instead of spreading as it leaves the propeller, is directed in a cylindrical columnto the rear, and thus the greatest thrust for forward propulsion is obtained. The concavity 16 at the base of the blade permits the water to leave the blade and establishes a current toward the hub, decreasing the cavitation effect.

Having thus described my invention, I claim as new and desire to secure by Letters Patent:

A propeller, comprising a plurality of concave-convex blades, the rear edge of blade terminating at the base of the blade approximately in line with the forward edge of the following blade, the concave face of each blade presenting a curve of increasing radius from the base line outwardly to a point beyond the transverse center, from which point the curve is of decreasing radius to the outer edge, the concave face presenting transversely a curve of increasing radius from the forward edge to a point at about the longitudinal center, and then a curve of decreasing radius to the rear edge, the outer edge of each blade presenting a convex curve of increasing radius from the base to a point short of the longitudinal In testimony whereof I have signed my center and then presenting a curve of dename to this specification in the presence of creasing radiusto a point on the rear edge two subscribing vwitnesses. inward beyond the transverse center of the HERBERT D. F. BAGLEY.

5 blade, from which latter point the rear edge Witnesses:

of the blade presents a concave curve eX- JOHN A, WHITTAKER, tending to the base line. ANDREW J. BAGLEY, Jr.

' Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. G. 

